An exception to throw in the default branch of a switch..case that ought to be exhaustive

EnumSwitchException.cs

using System;

namespace Example
{
    /// <summary>
    /// </summary>
    /// <typeparam name="T">Must be an enum type</typeparam>
    /// <remarks>
    /// Follows the pattern of <see cref="SwitchExpressionException"/>
    /// </remarks>
    public class EnumSwitchException<T> : InvalidOperationException
        where T : Enum
    {
        public EnumSwitchException(T actualValue)
            : base(
                $"Some values of the enum {typeof(T)} are not processed inside switch: {actualValue}"
            )
        {
        }
    }
}

Use like:

public string Convert(SomeEnum arg)
{
  return arg switch
  {
    SomeEnum.A => "branch a",
    SomeEnum.B => "branch b",
    _ => throw new EnumSwitchException<SomeEnum>(arg),
  };
}